Field of the Invention
The present invention relates to a radiation-sensitive resin composition and a resist pattern-forming method.
Discussion of the Background
According to chemically amplified radiation-sensitive resin compositions, an acid is generated from an acid generator in light-exposed regions upon irradiation with exposure light such as an ArF excimer laser beam or a KrF excimer laser beam, and a reaction permitted by this acid as a catalyst causes alteration of the rate of dissolution in a developer solution at the light-exposed regions and light-unexposed regions, thereby enabling the resist pattern to be formed on a substrate.
Such radiation-sensitive resin compositions are demanded to exhibit superior lithography performances such as sensitivity and resolution along with increasingly minute processing techniques. To address such demands, a variety of structures of acid-labile groups which may be included in polymers in the radiation-sensitive resin compositions have been investigated, and those having a plurality of specific ring structures have been known (see Japanese Unexamined Patent Application, Publication No. 2011-43794). In addition, introduction of various polar groups into the polymer have been also studied, and those having a lactone ring structure have been known (see Japanese Unexamined Patent Application, Publication Nos. 2000-26446, 2000-159758, H10-207069 and H10-274852). These radiation-sensitive resin compositions can reportedly improve the resolution.
However, at present when microfabrication of the resist pattern has proceeded to a level for a line width of no greater than 40 nm, the radiation-sensitive resin compositions are required to exhibit a further superior resolution described above, and desired to exhibit not only superior rectangularity of cross-sectional shape, as well as superior LWR (Line Width Roughness) performance that is an indicating variance of line widths, and CDU (Critical Dimension Uniformity) performance that is an indicative of variance of the line widths in greater ranges, but also favorable depth of focus (DOF) and exposure latitude, thereby enabling a pattern with high accuracy to be formed in a high process yield.